Roll mills, particularly so-called spring-loaded roller mills, of the type to which the invention relates are well known in the art. These roll mills are used for the comminution of different granular or lumpy materials, such as for example cement materials, ores, coal or the like. One embodiment of these roller mills is known for example from DE-B-12 50 724. In this case the two rollers of a pair of rollers are held so as to be freely rotatable one on each side of a roller support, and in the case of a floating mounting they are reciprocally supported on a roller shaft. The two ends of each roller support project outwards over the periphery of the grinding table and at approximately the height of the grinding roller shaft they are vertically guided via outer guide pins or bolts in housing guides, linkage points for the upper ends of the tension rods being constructed above these guides. One advantage of these known roll mills with pairs of grinding rollers is that each grinding roller of a pair can be adapted in its peripheral speed to that of the appertaining (outer or inner) region of the grinding surface or track, so that the wear on the periphery of the grinding rollers can be kept comparatively low.
In the practical comminuting operation of these known roll mill constructions, on the grinding surface the movement of the material for grinding and the resulting centrifugal forces give rise to radial forces which, through the friction which occurs, attempt to tip the grinding rollers about the guide pins of the roller support, i.e. tipping moments which act on the appertaining pair of grinding rollers are produced about the vertical guides of each roller support. With this friction which occurs particularly between the material for grinding and the grinding rollers, the coefficient of friction thereof alters according to the different conditions of the material for grinding (grain sizes, moistness of the material, density of the material bed, thickness of the material bed, etc.), as a result of which different tipping moments can occur constantly which lead to an additional constant movement in the bed of material for grinding and thus disrupt the comminuting operation.
The object of the invention, therefore, is to improve a roll mill of the type referred to in such a way that with a relatively simple construction undesirable moments of rotation or of tipping in the region of each pair of grinding rollers and of each appertaining roller support are reliably avoided and particularly smooth running of the roll mill is ensured.